The present invention relates to a power control device and a power control method, particularly to a power control device and a power control method for being able to stably output power during autonomous output.
Nowadays, a solar power generation system provided with a solar power generation panel and a storage battery is in widespread use. In the solar power generation system, after DC voltage power generated by the solar power generation panel is converted into AC voltage power by a power conditioner, the AC voltage power is supplied to and consumed by a load, or returned to a commercial power system and sold. The power is stably supplied regardless of weather by recharging a storage battery with the power generated by the solar power generation panel.
For example, Patent Document 1 (Japanese Unexamined Patent Publication No. 2002-142460) discloses a power conversion device that converts the DC voltage power generated by the solar power generation panel into the AC voltage power. Patent Document 2 (Japanese Unexamined Patent Publication No. 2002-112461) discloses a power conversion device that can detect a system voltage of a power system to switch between output voltages of AC voltages of 100 V and 200 V.
When power outage is generated to stop supply of the power from the commercial power system, the solar power generation system becomes an autonomous operation mode in which an autonomous operation is performed independently of the commercial power system. In the autonomous operation mode, the power generated by the solar power generation panel or the power stored in the storage battery is converted into the power of the AC voltage of 100 V by the power conditioner and supplied to the load.
However, in the solar power generation system, the voltage of the power output from the solar power generation panel decreases largely when the power conditioner makes a request to the solar power generation panel to supply the excessively large power during the autonomous output caused by the power outage. Therefore, the power generated by the solar power generation panel decreases temporarily significantly, and sometimes the power is hardly stably output.
The present invention has been devised to solve the problems described above, and an object thereof is to be able to stably output the power during the autonomous output.